The present invention relates to a method for producing a reinforcement member of composite material with an omega-like cross section.
In the aeronautical field, reinforcement members are used in order to increase the mechanical characteristics of some elements, such as, for example, the panels which form the fuselage.
In geometrical terms, as illustrated in FIG. 1A, the cross section of a reinforcement member 10 comprises, on the one hand, a central portion in the form of a U or a V, with at least two inclined faces 12, 12′ which are optionally connected by means of a central face 14 and, on the other hand, at each side, wings 16, 16′ which form abutment surfaces.
In known manner, a reinforcement member of composite material comprises fibers which are embedded in a resin matrix. In accordance with the desired features, the fibers have to comply with specific orientations.
According to a known embodiment, a reinforcement member of composite material is obtained by means of draping sheets or layers of pre-impregnated fibers on a mold which comprises an upper die whose shapes are adapted to the central portion of the reinforcement member.
According to a first operating method, the draping of the sheets of flexible fibers is carried out manually, sheet by sheet, in order to ensure the correct orientation of the fibers of the different sheets and to limit the risks of bridging between the sheets in the region of the connection zones between the inclined faces 12, 12′ and the wings 16, 16′.
Subsequently, the stack of the fiber sheets is subjected to a baking cycle. Even if this operating method allows the risks of non-conformity of the reinforcement member to be limited, it is not completely satisfactory since the manual draping operations tend to increase the time and the costs of production.
In the field of draping, there are depositing machines which allow the draping to be automated in order to reduce the time and the production costs.
However, these machines are adapted for depositing sheets in the flat state and are not suitable for depositing sheets on an upper die.
In the field of producing a component of composite material, a technique of hot-forming is known which involves producing a planar preform of fiber sheets using a depositing machine, heating the planar preform to a specific temperature which is lower than the polymerization temperature but which allows the fiber sheets to slide relative to each other, then deforming the preform on a mold in order to obtain the desired form.
This technique cannot be used in this state for producing reinforcement members since it systematically leads to the appearance of a defect 18 (illustrated in FIG. 1B), in particular in the region of the connection zones between the inclined faces 12, 12′ and the wings 16, 16′.